Ursolic acid inhibits Th17 cell differentiation via STAT3/RORγt pathway and suppresses Schwann cell-mediated Th17 cell migration by reducing CXCL9/10 expression.

Th17 cells represent important immune cells. Ursolic acid (UA) can regulate immune cell activities. This study was aimed to explore the effects of UA on Th17 cell differentiation and Schwann cell(SCs)-mediated migration and the potential mechanism. Naïve CD4+ T cells were isolated from rat peripheral blood, induced for Th17 cell differentiation, and treated with UA. The proportion of Th17 cells was detected by flow cytometry assay. SCs were co-cultured with Th17 cells. Th17 cell migration was detected by Transwell assay. The molecule expression was determined by Western blot and qRT-PCR. UA inhibited the Th17 cell differentiation and suppressed the STAT3/RORγt pathway. STAT3 overexpression up-regulated p-STAT3 and RORγt expression and promoted Th17 cell differentiation under the UA treatment. In LPS- and IFN-γ-stimulated-SCs, UA suppressed the expression of chemokines CXCL9/10, but had no significant effect of CCL20 expression. The expression CXCL9/10 receptor CXCR3 was higher in Th17 cells than that in Treg cells, while the expression CCL20 receptor CCR6 was lower in Th17 cells than that in Treg cells. UA, anti-CXCR3, and anti-CCR6 treatment inhibited SCs-mediated Th17 cell migration, and anti-CXCR3 exerted stronger inhibitory effect than Anti-CCR6. UA inhibited Th17 cell differentiation through STAT3/RORγt pathway and suppressed Th17 cell migration through down-regulating CXCL9/10 expression in SCs.

Radiation therapy enhanced therapeutic efficacy of anti-PD1 against gastric cancer.

Radiation therapy is an important method in tumor treatment with distinct responses. This study aimed to investigate the immune effects of radiation therapy on the syngeneic gastric tumor model. Mouse forestomach carcinoma (MFC) cells were irradiated with different X-ray doses. Cell proliferation was determined by clonogenic assay. Gene and protein expression were determined by real-time quantitative PCR and western blot, respectively. The tumor model was established by subcutaneously injecting tumor cells in 615-(H-2 K) mice. Levels of immune-related factors in tumor tissues were determined by immunohistochemistry and flow cytometry. 5 Gy × 3 (three subfractions with 4 h interval) treatment significantly inhibited cell proliferation. Protein expression of stimulator of interferon genes (Sting) and gene expression of IFNB1, TNFα as well as CXCL-9 significantly increased in MFC cells after irradiation. In the MFC mouse model, no obvious tumor regression was observed after irradiation treatment. Further studies showed Sting protein expression, infiltration of dendritic cells and T cells, and significantly increased PD-1/PD-L1 expression in tumor tissues. Moreover, the irradiation treatment activated T cells and enhanced the therapeutic effects of anti-PD1 antibody against MFC tumor. Our data demonstrated that although the MFC tumor was not sensitive to radiation therapy, the tumor microenvironment could be primed after irradiation. Radiation therapy combined with immunotherapy can greatly improve anti-tumor activities in radiation therapy-insensitive tumor models.

Cordycepin Attenuates IFN-γ-Induced Macrophage IP-10 and Mig Expressions by Inhibiting STAT1 Activity in CFA-Induced Inflammation Mice Model.

Cordycepin, a natural derivative of adenosine, has been shown to exert pharmacological properties including anti-oxidation, antitumor, and immune regulation. It is reported that cordycepin is involved in the regulation of macrophage function. However, the effect of cordycepin on inflammatory cell infiltration in inflammation remains ambiguous. In this study, we investigated the potential role of cordycepin playing in macrophage function in CFA-induced inflammation mice model. In this model, we found that cordycepin prevented against macrophage infiltration in paw tissue and reduced interferon-γ (IFN-γ) production in both serum and paw tissue. Using luciferase reporter assay, we found that cordycepin suppressed IFN-γ-induced activators of transcription-1 (STAT1) transcriptional activity in a dose-dependent manner. Moreover, western blotting data demonstrated that cordycepin inhibited IFN-γ-induced STAT1 activation through attenuating STAT1 phosphorylation. Further investigations revealed that cordycepin inhibited the expressions of IFN-γ-inducible protein 10 (IP-10) and monokine induced by IFN-γ (Mig), which were the effector genes in IFN-γ-induced STAT1 signaling. Meanwhile, the excessive inflammatory cell infiltration in paw tissue was reduced by cordycepin. These findings demonstrate that cordycepin alleviates excessive inflammatory cell infiltration through down-regulation of macrophage IP-10 and Mig expressions via suppressing STAT1 phosphorylation. Thus, cordycepin may be a potential therapeutic approach to prevent and treat inflammation-associated diseases.

Theiler's murine encephalomyelitis virus infection of astrocytes induces the expression of chemokines which attract activated but not resting T lymphocytes.

In this article, we studied the production of the chemokine CXCL9, also termed Mig (monokine induced by gamma interferon) by cultured SJL/J mouse astrocytes infected with the BeAn strain of Theiler's murine encephalomyelitis virus (TMEV). This picornavirus induces demyelination in the SJL/J genetically susceptible strain of mice through an immune process mediated by CD4+ Th1 T cells. Those cells were chemoattracted by chemokines inside the central nervous system (CNS) after blood-brain barrier (BBB) disruption.cRNAs from TMEV- and mock-infected astrocytes cells were hybridized to the Affymetrix murine genome U74v2 DNA microarray. Hybridization data analysis revealed the upregulation of six sequences potentially coding for Mig. We confirmed post infection Mig mRNA increase by quantitative (qPCR) and RT-PCR. The presence of Mig in the supernatants of infected astrocytes was quantified using a specific ELISA. Secreted Mig was biologically active, inducing chemoattraction of mouse activated CD4+ T lymphocytes. Conversely, attracting activity on CD3+ resting T cells that can be attributed to chemokines as CXCL12/SDF-1α could not be demonstrated in these supernatants. No overinduction of the gene coding for this chemokine was assessed by DNA hybridization either. Both recombinant IFN-γ and TNF-α inflammatory cytokines were also strong inducers of Mig in SJL/J astrocyte cultures.

Reactive oxygen species stimulated pulmonary epithelial cells mediate the alveolar recruitment of FasL+ killer B cells in LPS-induced acute lung injuries.

Reactive oxygen species (ROS) are electrophilic chemical species produced from incomplete oxidation. They have long been known as aggressive molecules that lead to direct tissue and cellular damage. Recent studies have reconsidered ROS as second messengers in the initiation and amplification of cell signaling, but how ROS regulate lung tissue and immune cell remain unknown. In this study, we used a LPS-induced acute lung injury (ALI) mouse model to observe disease, progression and determine ROS-related immune responses. We found that ROS play an essential pathogenic role in ALI, however, the major role of ROS in exacerbating ALI was increasing bronchoalveolar fluid (BALF) B cells rather than eliciting tissue damage. Moreover, these pathogenic B cells are FasL+ killer B cells, which reported to damage Fas-sensitive target cells including pulmonary epithelial cells. Furthermore, via in vitro transwell assays and in vivo treatment with neutralizing antibodies. ROS promoted pulmonary epithelial cells to produce CXCL9 and CXCL10, which recruited B cells into BALF. These results demonstrated that during lung injury, instead of causing oxidative damage, ROS mainly serve as second messengers, interacting with tissue and immune cells to enhance immune responses that lead to more severe disease.

CXCL9, CXCL10, CXCL11, and their receptor (CXCR3) in neuroinflammation and neurodegeneration.

The aim of this review is to present data from the available literature concerning CXCL9, CXCL10 and CXCL11, as well as their receptor 3 (CXCR3) in selected diseases of the central nervous system (CNS), such as tickborne encephalitis (TBE), neuroborreliosis (NB), Alzheimer's disease (AD), and multiple sclerosis (MS). CXCL9, CXCL10, and CXCL11 lack glutamic acid-leucine-arginine (ELR), and are unique, because they are more closely related to each other than to any other chemokine. The aforementioned chemokines are especially involved in Th1-type response and in various diseases, as their expression correlates with the tissue infiltration of T cells. Their production is strongly induced by interferon gamma (IFN-υ), the most typical Th1 cytokine. They act by binding to the CXC3 receptor. Knowledge about the action mechanism of CXCR3 and its ligands may be useful in the treatment of CNS diseases. However, data in the literature concerning the evaluation of CXCL9, CXCL10, CXCL11, and their receptor with the use of the enzyme-linked immunosorbent assay (ELISA) method is limited.

Sulforaphane inhibits the interferon-γ-induced expression of MIG, IP-10 and I-TAC in INS­1 pancreatic ß-cells through the downregulation of IRF-1, STAT-1 and PKB.

Sulforaphane (SFN) is a dietary isothiocyanate abundantly available in cruciferous vegetables and has been shown to possess anti-inflammatory and immunomodulatory activities. Chemokines are important mediators of inflammation and immune responses due to their ability to recruit and activate macrophages and leukocytes. To date, little is known about the SFN-mediated regulation of chemokine expression in pancreatic ß-cells. In this study, we investigated the inhibitory effects and mechanisms of SFN on the interferon-γ (IFN-γ)-induced expression of a subset of chemokines, including monokine induced by IFN-γ (MIG), IFN-inducible protein of 10 kDa (IP-10) and IFN-inducible T­cell alpha chemoattractant (I-TAC), in INS­1 cells, a rat pancreatic ß-cell line. Notably, IFN-γ treatment led to an increase in the mRNA expression levels of MIG, IP-10 and I-TAC in the INS­1 cells. However, SFN strongly blocked the mRNA expressions of MIG, IP-10 and I-TAC induced by IFN-γ in INS­1 cells. On the mechanistic level, SFN significanlty decreased not only the mRNA expression levels of interferon regulatory factor-1 (IRF-1), but also the phosphorylation levels of signal transducer and activator of transcription-1 (STAT-1) and protein kinase B (PKB) which were induced by IFN-γ in the INS­1 cells. Pharmacological inhibition experiments further revealed that treatment with JAK inhibitor I weakly inhibited the IFN-γ-induced expression of IP-10, whereas it strongly suppressed the IFN-γ-induced expression of MIG and I-TAC in the INS­1 cells. Moreover, treatment with LY294002, a PI3K/PKB inhibitor, was able to slightly repress IFN­Î³­induced expressions of MIG and I-TAC, but not IP-10, in INS­1 cells. Importantly, the IFN-γ-induced increase in the expression levels of MIG, IP-10 and I-TAC in the INS-1 cells was strongly inhibited by SFN, but not by other natural substances, such as curcumin, sanguinarine, resveratrol, triptolide and epigallocatechin gallate (EGCG), suggesting the specificity of SFN in downregulating the levels of these chemokines. To the best of our knowledge, these results collectively demonstrate for the first time that SFN strongly inhibits the IFN-γ-induced expression of MIG, IP-10 and I-TAC in INS­1 cells and this inhibition is, at least in part, mediated through the reduced expression and phosphorylation levels of IRF-1, STAT-1 and PKB.

Transcriptional and Cytokine Profiles Identify CXCL9 as a Biomarker of Disease Activity in Morphea.

IFN-related pathways have not been studied in morphea, and biomarkers are needed. We sought to characterize morphea serum cytokine imbalance and IFN-related gene expression in blood and skin to address this gap by performing a case-control study of 87 participants with morphea and 26 healthy control subjects. We used multiplexed immunoassays to determine serum cytokine concentrations, performed transcriptional profiling of whole blood and lesional morphea skin, and used double-staining immunohistochemistry to determine the cutaneous cellular source of CXCL9. We found that CXCL9 was present at increased concentrations in morphea serum (P < 0.0001), as were other T helper type 1 cytokines. CXCL9 serum concentration correlated with the modified Localized Scleroderma Skin Severity Index (r = 0.44, P = 0.0001), a validated measure of disease activity. CXCL9 gene expression was also increased in inflammatory lesional morphea skin (fold change = 30.6, P = 0.006), and preliminary transcriptional profiling showed little evidence for IFN signature in whole blood. Double-staining immunohistochemistry showed CXCL9 co-localized with CD68+ dermal macrophages. In summary, inflammatory morphea is characterized by T helper type 1 cytokine imbalance in serum, particularly CXCL9, which is associated with disease activity. CXCL9 expression in lesional macrophages implicates the skin as the source of circulating cytokines. CXCL9 is a promising biomarker of disease activity in morphea.

Murine liver-resident group 1 innate lymphoid cells regulate optimal priming of anti-viral CD8+ T cells.

The liver contains 2 transcriptionally distinct group 1 ILC subsets: CD49a+ ILC1s and CD49b+ NK cells. However, little is known about how group 1 ILCs contribute to hepatic immune responses. Therefore, we characterized murine liver-resident group 1 ILCs and found that CD49a+ ILC1s express high levels of the inhibitory receptor NKG2A and localize near DCs in perivascular spaces surrounding the portal triads. Upon hepatic viral infection, NKG2A signaling in group 1 ILCs, especially in CD49a+ ILC1s, inhibits CXCL9 expression required for robust accumulation of IFN-γ+CD49b+ NK cells. As a consequence, NKG2A-/- mice showed increased numbers of IFN-γ-producing NK cells that preferentially activate liver CD103+ DCs, leading to the sustained proliferation of adoptively transferred, virus-specific CD8+ T cells. Collectively, these data suggest that group 1 ILCs play a role in maintaining the liver as a tolerogenic site by limiting the recruitment of peripheral NK cells during the early phase of viral infection. Furthermore, our findings implicate that the inhibition of NKG2A signaling on group 1 ILCs may be a novel vaccine strategy to induce robust CD8+ T cell responses against persistent liver pathogens.

Ectopic expression of the chemokine CXCL17 in colon cancer cells.

BACKGROUND: The novel chemokine CXCL17 acts as chemoattractant for monocytes, macrophages and dendritic cells. CXCL17 also has a role in angiogenesis of importance for tumour development. METHODS: Expression of CXCL17, CXCL10, CXCL9 and CCL2 was assessed in primary colon cancer tumours, colon carcinoma cell lines and normal colon tissue at mRNA and protein levels by real-time qRT-PCR, immunohistochemistry, two-colour immunofluorescence and immunomorphometry. RESULTS: CXCL17 mRNA was expressed at 8000 times higher levels in primary tumours than in normal colon (P < 0.0001). CXCL17 protein was seen in 17.2% of cells in tumours as compared with 0.07% in normal colon (P = 0.0002). CXCL10, CXCL9 and CCL2 mRNAs were elevated in tumours but did not reach the levels of CXCL17. CXCL17 and CCL2 mRNA levels were significantly correlated in tumours. Concordant with the mRNA results, CXCL10- and CXCL9-positive cells were detected in tumour tissue, but at significantly lower numbers than CXCL17. Two-colour immunofluorescence and single-colour staining of consecutive sections for CXCL17 and the epithelial cell markers carcinoembryonic antigen and BerEP4 demonstrated that colon carcinoma tumour cells indeed expressed CXCL17. CONCLUSIONS: CXCL17 is ectopically expressed in primary colon cancer tumours. As CXCL17 enhances angiogenesis and attracts immune cells, its expression could be informative for prognosis in colon cancer patients.

XCR1+ dendritic cells promote memory CD8+ T cell recall upon secondary infections with Listeria monocytogenes or certain viruses.

Naive CD8(+) T cell priming during tumor development or many primary infections requires cross-presentation by XCR1(+) dendritic cells (DCs). Memory CD8(+) T lymphocytes (mCTLs) harbor a lower activation threshold as compared with naive cells. However, whether their recall responses depend on XCR1(+) DCs is unknown. By using a new mouse model allowing fluorescent tracking and conditional depletion of XCR1(+) DCs, we demonstrate a differential requirement of these cells for mCTL recall during secondary infections by different pathogens. XCR1(+) DCs were instrumental to promote this function upon secondary challenges with Listeria monocytogenes, vesicular stomatitis virus, or Vaccinia virus, but dispensable in the case of mouse cytomegalovirus. We deciphered how XCR1(+) DCs promote mCTL recall upon secondary infections with Listeria. By visualizing for the first time the in vivo choreography of XCR1(+) DCs, NK cells and mCTLs during secondary immune responses, and by neutralizing in vivo candidate molecules, we demonstrate that, very early after infection, mCTLs are activated, and attracted in a CXCR3-dependent manner, by NK cell-boosted, IL-12-, and CXCL9-producing XCR1(+) DCs. Hence, depending on the infectious agent, strong recall of mCTLs during secondary challenges can require cytokine- and chemokine-dependent cross-talk with XCR1(+) DCs and NK cells.

Extracellular Histones Induce Chemokine Production in Whole Blood Ex Vivo and Leukocyte Recruitment In Vivo.

The innate immune system relies to a great deal on the interaction of pattern recognition receptors with pathogen- or damage-associated molecular pattern molecules. Extracellular histones belong to the latter group and their release has been described to contribute to the induction of systemic inflammatory reactions. However, little is known about their functions in the early immune response to an invading pathogen. Here we show that extracellular histones specifically target monocytes in human blood and this evokes the mobilization of the chemotactic chemokines CXCL9 and CXCL10 from these cells. The chemokine induction involves the toll-like receptor 4/myeloid differentiation factor 2 complex on monocytes, and is under the control of interferon-γ. Consequently, subcutaneous challenge with extracellular histones results in elevated levels of CXCL10 in a murine air pouch model and an influx of leukocytes to the site of injection in a TLR4 dependent manner. When analyzing tissue biopsies from patients with necrotizing fasciitis caused by Streptococcus pyogenes, extracellular histone H4 and CXCL10 are immunostained in necrotic, but not healthy tissue. Collectively, these results show for the first time that extracellular histones have an important function as chemoattractants as their local release triggers the recruitment of immune cells to the site of infection.

CD11b deficiency suppresses intestinal tumor growth by reducing myeloid cell recruitment.

Mac-1 (CD11b) is expressed on bone marrow-derived immune cells. CD11b binds to ligands to regulate leukocyte adhesion and migration across the endothelium or epithelium. Here, we employed CD11b knockout mice and an Apc(Min/+) spontaneous intestinal adenoma mouse model to clarify the function of CD11b in intestinal tumorigenesis. We showed that CD11b deficiency may contribute to the inhibition of myeloid cell trafficking to the tumor microenvironment and inactivated Wnt/ß-catenin pathway to suppress tumor growth. This effect was partly mediated by inhibiting the myeloid cell-mediated decrease in TNF-α secretion, which inhibits the recruitment of myeloid-derived suppressor cells to the tumor microenvironment and subsequently induces IFN-γ and CXCL9 production. This work provides evidence for the mechanism by which CD11b may function as an important oncogene and highlights the potential of CD11b as a therapeutic target in CRC.

Epigenetic silencing of TH1-type chemokines shapes tumour immunity and immunotherapy.

Epigenetic silencing including histone modifications and DNA methylation is an important tumorigenic mechanism. However, its role in cancer immunopathology and immunotherapy is poorly understood. Using human ovarian cancers as our model, here we show that enhancer of zeste homologue 2 (EZH2)-mediated histone H3 lysine 27 trimethylation (H3K27me3) and DNA methyltransferase 1 (DNMT1)-mediated DNA methylation repress the tumour production of T helper 1 (TH1)-type chemokines CXCL9 and CXCL10, and subsequently determine effector T-cell trafficking to the tumour microenvironment. Treatment with epigenetic modulators removes the repression and increases effector T-cell tumour infiltration, slows down tumour progression, and improves the therapeutic efficacy of programmed death-ligand 1 (PD-L1; also known as B7-H1) checkpoint blockade and adoptive T-cell transfusion in tumour-bearing mice. Moreover, tumour EZH2 and DNMT1 are negatively associated with tumour-infiltrating CD8(+) T cells and patient outcome. Thus, epigenetic silencing of TH1-type chemokines is a novel immune-evasion mechanism of tumours. Selective epigenetic reprogramming alters the T-cell landscape in cancer and may enhance the clinical efficacy of cancer therapy.

STAT3 Inhibition Enhances the Therapeutic Efficacy of Immunogenic Chemotherapy by Stimulating Type 1 Interferon Production by Cancer Cells.

STAT3 is an oncogenic transcription factor with potent immunosuppressive functions. We found that pharmacologic inhibition of STAT3 or its selective knockout in cancer cells improved the tumor growth-inhibitory efficacy of anthracycline-based chemotherapies. This combined effect of STAT3 inhibition/depletion and anthracyclines was only found in tumors growing on immunocompetent (not in immunodeficient) mice. As compared with Stat3-sufficient control tumors, Stat3(-/-) cancer cells exhibited an increased infiltration by dendritic cells and cytotoxic T lymphocytes after chemotherapy. Anthracyclines are known to induce several stress pathways that enhance the immunogenicity of dying and dead cancer cells, thereby stimulating a dendritic cell-dependent and T lymphocyte-mediated anticancer immune response. Among these therapy-relevant stress pathways, Stat3(-/-) cancer cells manifested one significant improvement, namely an increase in the expression of multiple type-1 interferon-responsive genes, including that of the chemokines Cxcl9 and Cxcl10. This enhanced type-1 interferon response could be suppressed by reintroducing wild-type Stat3 (but not a transactivation-deficient mutant Stat3(Y705F)) into the tumor cells. This maneuver also abolished the improved chemotherapeutic response of Stat3(-/-) cancers. Finally, the neutralization of the common type-1 interferon receptor or that of the chemokine receptor CXCR3 (which binds CXCL9 and CXCL10) abolished the difference in the chemotherapeutic response between Stat3(-/-) and control tumors. Altogether, these results suggest that STAT3 inhibitors may improve the outcome of chemotherapy by enhancing the type-1 interferon response of cancer cells.

CXCR3 blockade protects against Listeria monocytogenes infection-induced fetal wastage.

Mammalian pregnancy requires protection against immunological rejection of the developing fetus bearing discordant paternal antigens. Immune evasion in this developmental context entails silenced expression of chemoattractant proteins (chemokines), thereby preventing harmful immune cells from penetrating the maternal-fetal interface. Here, we demonstrate that fetal wastage triggered by prenatal Listeria monocytogenes infection is driven by placental recruitment of CXCL9-producing inflammatory neutrophils and macrophages that promote infiltration of fetal-specific T cells into the decidua. Maternal CD8+ T cells with fetal specificity upregulated expression of the chemokine receptor CXCR3 and, together with neutrophils and macrophages, were essential for L. monocytogenes-induced fetal resorption. Conversely, decidual accumulation of maternal T cells with fetal specificity and fetal wastage were extinguished by CXCR3 blockade or in CXCR3-deficient mice. Remarkably, protection against fetal wastage and in utero L. monocytogenes invasion was maintained even when CXCR3 neutralization was initiated after infection, and this protective effect extended to fetal resorption triggered by partial ablation of immune-suppressive maternal Tregs, which expand during pregnancy to sustain fetal tolerance. Together, our results indicate that functionally overriding chemokine silencing at the maternal-fetal interface promotes the pathogenesis of prenatal infection and suggest that therapeutically reinforcing this pathway represents a universal approach for mitigating immune-mediated pregnancy complications.

The CXCR3 chemokines in inflammatory myopathies.

The α-chemokines (C-X-C motif) ligand 9 (CXCL9) and interferon γ-induced protein 10 (IP-10) are expressed in idiopathic inflammatory myopathies muscle. Abundant expression of IP-10 was observed on macrophages and T cells surrounding and invading non-necrotic muscle fibers in polymyositis and sporadic inclusion body myositis and in T cells in perimysial infiltrates of dermatomyositis. IP-10 was also localized to blood vessel endothelial cells in all inflammatory and normal muscle tissues. Serum IP-10 is high in patients with inflammatory myopathies. Human skeletal muscle cells might actively self-promote muscular inflammation by eliciting IP-10 secretion, under the influence of cytokines [Interferon (IFN-γ), Tumor Necrosis Factor (TNF-α)], which can amplify T helper (Th)1 cell tissue infiltration in vivo. It has been shown that drugs able to block the IP-10/chemokine (C-X-C motif) receptor 3 (CXCR3) axis can suppress inflammation in muscle.

Cytokines and chemokines in multiple sclerosis.

Chemokine (C-X-C motif) receptor 3 (CXCR3) and its ligands (MIG, IP-10) play an important role in multiple sclerosis (MS). The CXCR3 receptor is expressed on the majority of T cells in the cerebrospinal fluid (CSF) of patients with MS, suggesting that the CXCR3 receptor may mediate the trafficking of T cells into the central nervous system. IP-10, and MIG were found to be elevated in the CSF of patients with MS during relapse. These chemokines were also detected in actively demyelinating lesions, and upregulation of CXCR3 expression on peripheral blood CD4+ lymphocytes was associated with MS relapses.Treatment with Interferon (IFN)-ß-1a or IFN-ß-1b was associated with increased IP-10. Natalizumab that exerts impressive therapeutic effects in patients with MS induces a marked decline of Th1 chemokines (MIG, IP-10, I-TAC) in CSF.

Polyclonal, newly derived T cells with low expression of inhibitory molecule PD-1 in tonsils define the phenotype of lymphocytes in children with Periodic Fever, Aphtous Stomatitis, Pharyngitis and Adenitis (PFAPA) syndrome.

PURPOSE: PFAPA syndrome is a benign, recurrent inflammatory disease of childhood. Tonsillectomy is one of the therapeutic options with a yet unexplained biological mechanism. We tested whether specific lymphocyte subsets recruited from blood to human tonsils participate in PFAPA pathogenesis. METHODS: Paired tonsils/peripheral blood (PB) samples were investigated (a) from children with PFAPA that successfully resolved after tonsillectomy (n=10) (b) from children with obstructive sleep apnoea syndrome as controls (n=10). The lymphocyte profiles were analysed using 8-colour flow cytometry, immunoglobulin (IGH) and T-cell receptor (TCR) gene rearrangements via PCR and next generation sequencing; a TREC/KREC analysis was performed using qPCR. RESULTS: The PFAPA tonsils in the asymptomatic phase had a lower percentage of B-lymphocytes than controls; T-lymphocyte counts were significantly higher in PB. The percentages of cytotoxic CD8pos T-lymphocytes were approximately 2-fold higher in PFAPA tonsils; the transitional B cells and naïve stages of both the CD4pos and CD8pos T-lymphocytes with a low expression of PD-1 molecule and high numbers of TREC were also increased. With the exception of elevated plasmablasts, no other differences were significant in PB. The expression levels of CXCL10, CXCL9 and CCL19 genes were significantly higher in PFAPA tonsils. The IGH/TCR pattern showed no clonal/oligoclonal expansion. DNA from the Epstein-Barr virus, Human Herpervirus-6 or adenovirus was detected in 7 of 10 PFAPA tonsils but also in 7 of 9 controls. CONCLUSIONS: Our findings suggest that the uninhibited, polyclonal response of newly derived lymphocytes participate in the pathogenesis of PFAPA. Because most of the observed changes were restricted to tonsils and were not present in PB, they partly explain the therapeutic success of tonsillectomy in PFAPA syndrome.

Bcl-3 puts the brakes on contact hypersensitivity.

B-cell lymphoma (Bcl)-3 is a nonclassical member of the IκB protein family known to interact with transcriptionally inactive NF-κB1 and NF-κB2 homodimers to modulate gene expression. Besides its action as an oncoprotein, Bcl-3 has been shown to have both proinflammatory and anti-inflammatory functions depending on the cell-type affected. In this issue of the European Journal of Immunology, Tassi et al. [Eur. J. Immunol. 2015. 45: 1059-1068] report that Bcl-3 inhibits the production of the proinflammatory chemokines CXCL9 and CXCL10 in keratinocytes, thereby restricting the influx of CD8(+) effector T cells in a mouse model of allergic contact dermatitis. In addition, mice with a global deficiency of Bcl-3 show enhanced ear swelling responses in the late phase of contact hypersensitivity responses. Besides keratinocytes, other radioresistant cell types appear to also utilize Bcl-3 to dampen the inflammatory response. This Commentary will discuss the evidence supporting Bcl-3 as a critical player in limiting inflammation during the later stages of contact hypersensitivity.